Trends & Indicators of Encroachment Association of California Airports 2007 Annual Fall Conference September 20, 2007 Lake Tahoe, CA

What is the problem? Airports are becoming centers of growth, just like rivers and railroads were in previous centuries. Land in areas adjacent to airports is being developed. Noise contours have been shrinking, but are projected to increase again with traffic growth. Are federal and local authorities playing their part in mitigating noise in the community? Is population encroachment occurring – Inside the DNL 65 contour? – Outside the DNL 65 contour? And if so, what can be done about it?

Study Purpose Provide sound scientific understanding of land use and population dynamics around commercial airports in order to create effective land use and noise policies Identify factors, trends, and patterns of “encroachment” Assess potential and future land use conflicts Create effective land use management strategies

Approach Construct techniques and measures to capture the pattern of residential land uses around airports Determine the extent to which residential populations are aggregating near airports Examine the underlying factors influencing “encroachment patterns” near commercial airports Study the connection between airports, suburbanization, and the spatial expansion of cities Evaluate strategies to mitigate the land use conflicts

92 Study Airports

Areas of Interest Land inside the Average Day-Night Sound Level (DNL) 65 dB Contour Land in the released areas of changing DNL contours Land adjacent to commercial airports and outside established noise contours

Released Land

Measures of Encroachment Census Land Cover Land Use Remote Sensing Spatial Metrics Zoning

Census

Changes in Population and Housing Inside the DNL 65 Contour at 92 US Airports

1990 Census Data2000 Census Data Base CasePopulation Change Noise LevelPopulationChangeHousingChangePopulationChangeHousingChange 1990 DNL 55dB to less than 60dB NA NA % % 60dB to less than 65dB % % 65dB to less than 70dB % % 70dB to less than 75dB % % 75dB % % Noise ChangePopulation Change 2001 DNL 55dB to less than 60dB % % % % 60dB to less than 65dB % % % % 65dB to less than 70dB % % % % 70dB to less than 75dB % % % % 75dB % % % %

Changes in Population and Housing in Released Land

Number of Airports with Housing Increase on the Released Lands

Number of Airports with Changes in Housing Densities between 1 to 10-mile radius from the Airport Reference Point,

Land Cover

Area (Acres) Change Undeveloped Land % Developed Land % 1992 NLCD vs NLCD Inside a 10-mile Radius

Movement of Population-Weighted Center* * Inside a 10-mile radius

Recap: General Trends Little evidence of people moving inside the DNL 65 dB contours – FAA guidelines seem to be effective Technology has dominated the reduction of overall noise exposure Evidence that people are aggregating immediately outside the DNL 65 dB contours Intensification of development occurring around airports Fifty-percent of the lands within 5 miles of an airport remain undeveloped and vulnerable to population encroachment

What Needs to Happen? It’s late, but not too late, for FAA to expand guidelines for non-compatible development to areas beyond the DNL 65 Local authorities need to limit non-compatible development outside the DNL 65 contour – establish buffer zones Establish incentives, such as environmental tax benefits, to limit development in vulnerable areas

What’s Next? What are the underlying factors influencing “encroachment patterns” near commercial airports? What is the connection between airports, suburbanization, and the spatial expansion of cities? Can we predict growth and future conflicts?